The image that shocked the world (centre), and led thousands including politicians (on left, Caroline Lucas of the Green Party) to say 'Refugees Welcome'

In the wake of the shocking picture of a dead child refugee washed ashore on a Turkish beach, a petition set up by the Independent newspaper has now been signed by more than 250,000 individuals, while The Independent-promoted hashtag #refugeeswelcome has been trending on Twitter, and Prime Minister David Cameron has come under pressure to act.

In an editorial on Thursday, The Independent said: "Europe is now at peace. But the continent cannot escape the impact of conflicts in the Middle East and Africa, which are driving innocent men, women and children in their millions to seek safety in the West."

The paper also encouraged readers to tweet a picture of themselves holding a sign saying 'Refugees Welcome', using the hashtag #refugeeswelcome. This has now been used by a range of politicians, celebrities and members of the public.

Much discussion has focussed on the power of the widely circulated picture, with the boy depicted since identified as three-year-old Aylan Kurdi.

Shimon Cohen – founder of agency The PR Office, whose grandparents fled oppression in Tsarist Russia and settled in Wales in 1910, said: "Photographs have always done this." He compared the image with that of Phan Thi Kim Phuc, a napalm attack victim shown with her clothes burnt away during the Vietnam War.

"I think that what the picture and The Independent's campaign have done is rebalance a debate that has gone wrong – somehow the issue of refugees has been conflated with the issue of immigration and it has been politicised, but immigration is a whole different debate."

Peter Gilheaney, director at social change comms agency Forster Communications, agreed, saying: "The old adage that a picture says a thousand words is especially true in a social media world – particularly when, in this case, the image of the young boy is juxtaposed with the PM's mealy mouthed justification for why the UK has accepted so few refugees and asylum seekers."

He said that The Independent's decision to take a stand was indicative of media outlets' business need to align ever more closely with the values of their audience. "Newspapers have always campaigned but I think this is indicative of an increasing trend for them to lose any sense of objectivity in their reporting. Their business model is under threat so they need other ways to bring in audience other than through readership," he said.

Becky Slack, founder of charity sector agency Slack Communications, said she felt charities had often been cautious in talking about the crisis previously – suggesting this may be due to a fear of upsetting government funders – but praised Médecins Sans Frontières/Doctors Without Borders for its use of "plain English", emotives stories and "strong statements about the reality of the situation".

"I’ve seen lots of comment from charities about ‘resettlement programmes’ and ‘co-ordinated efforts’ but little about the ‘human’," she said.

Slack said charities should now take the opportunity to speak out more clearly, saying: "For charities that support refugees, this is their PR moment. Never before has such a media spotlight been focused on their subject of their work. And yet, despite this, many of the statements from these organisations have been safe, measured and, in some cases, bland. As a result, these messages are getting lost and failing to make an impact."

Gilheaney said private firms as well as charities could consider speaking out, especially if it "chimes with an organisation's values and way of working". However, he warned: "If they are debating what's in it for them if they do, then they shouldn't get involved as it is very likely to come across at best as insincere and, at worst, as exploitative."